Low sulfur coal additive for improved furnace operation
First Claim
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1. A method for combusting coal, comprising:
- providing a coal-containing feed material to a coal combustion chamber;
contacting the feed material with an iron-containing additive, wherein the iron-containing additive is in the form of a free-flowing particulate having a P90 size of no more than about 300 microns; and
melting at least a portion of the coal-containing feed material and iron-containing additive to form a slag layer on at least a portion of a surface of the combustion chamber, whereby coal in the coal-containing feed material is captured by the slag layer and combusted.
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Abstract
The present invention is directed to additives for coal-fired furnaces, particularly furnaces using a layer of slag to capture coal particles for combustion. The additive(s) include iron, mineralizer(s), handling aid(s), flow aid(s), and/or abrasive material(s). The iron and mineralizers can lower the melting temperature of ash in low-iron, high alkali coals, leading to improved furnace performance.
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Citations
40 Claims
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1. A method for combusting coal, comprising:
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providing a coal-containing feed material to a coal combustion chamber;
contacting the feed material with an iron-containing additive, wherein the iron-containing additive is in the form of a free-flowing particulate having a P90 size of no more than about 300 microns; and
melting at least a portion of the coal-containing feed material and iron-containing additive to form a slag layer on at least a portion of a surface of the combustion chamber, whereby coal in the coal-containing feed material is captured by the slag layer and combusted. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for combusting coal, comprising:
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inputting a coal-containing feed material to a coal combustion chamber;
contacting the feed material with an iron-containing additive, wherein the iron-containing additive comprises at least about 50 wt. % (dry basis of the additive) iron and at least about 1 wt. % (dry basis of the additive) mineralizer; and
melting at least a portion of the coal-containing feed material and iron-containing additive to form a slag layer on at least a portion of a surface of the combustion chamber, whereby coal in the coal-containing feed material is captured by the slag layer and combusted. - View Dependent Claims (9, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20)
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15. A method for combusting coal, comprising:
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introducing a coal-containing feed material to a coal combustion chamber;
contacting the feed material with an iron-containing additive, wherein the iron-containing additive comprises at least about 50 wt. % (dry basis of the additive) iron and the iron is in the form of a mixture of ferrous and ferric oxides; and
melting at least a portion of the coal-containing feed material and iron-containing additive to form a slag layer on at least a portion of a surface of the combustion chamber, whereby coal in the coal-containing feed material is captured by the slag layer and combusted.
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21. An additive for a coal feed to a cyclone furnace, comprising:
iron in an amount of at least about 50 wt. % (dry basis of the additive), wherein the iron comprises at least about 33.5% of the iron is in the form of iron having a valence of +2 or lower and wherein the additive is in the form of a free-flowing particulate having a P90 size of no more than about 300 microns. - View Dependent Claims (22, 23, 24, 26, 27, 28, 29, 30, 31)
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25. A coal-containing feed material for a furnace, comprising:
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coal; and
an additive, wherein the additive includes;
iron in an amount of at least about 50 wt. % (dry basis of the additive) and a mineralizer in an amount of at least about 1 wt. % (dry basis of the additive).
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32. A slag layer in a coal-burning furnace, comprising:
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at least about 5 wt. % (dry basis of the slag layer) coal;
iron in an amount of at least about 15 wt. % (dry basis of the slag layer); and
a mineralizer in an amount of at least about 1 wt. % (dry basis of the slag layer). - View Dependent Claims (33, 34, 35, 36, 37, 38, 40)
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39. A solid byproduct of coal combustion, comprising:
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iron in an amount of at least about 15 wt. % (dry basis of the byproduct);
zinc in an amount of at least about 1 wt. % (dry basis of the byproduct);
silica compounds in an amount of at least about 2 wt. % (dry basis of the byproduct);
aluminum compounds in an amount of at least about 20 wt. % (dry basis of the byproduct); and
calcium compounds in an amount of at least about 15 wt. % (dry basis of the byproduct).
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Specification